The present invention relates to magnetic tape cassettes. More particularly, the invention relates to an improvement of a reel-to-reel type magnetic tape cassette, or a so-called Phillips-type magnetic tape cassette, in which a magnetic tape wound on a pair of winding cores is loaded between the upper and lower halves.
Magnetic tape cassettes are extensively employed for recording and reproducing audio signals. There has been a consistent demand for cassettes of high quality, namely, cassettes suitable for recording and reproducing signals with a high density and which have a long playing time.
Recently, digital recording systems such as the pulse code modulation (PCM) system have been employed for recording audio signals. In such a system, the signal recording density is very high. For instance, thirty-two tracks are typically formed on a tape having a width of 3.75 mm. Accordingly, the width of one track is of the order of 50 to 100 microns. That is, the width of each track is a fraction of the width of each track in a conventional recording system in which four tracks are formed on a tape.
Accordingly, in a conventional system of engaging a magnetic head with a tape in an audio apparatus, that is, in a signal recording and reproducing system in which a magnetic head is inserted into a cassette through its front opening, tracking error is liable to occur because the positioning accuracy of the head and the tape is low.
On the other hand, a system is known in which, as in a conventional video tape cassette, the tape is pulled out of the cassette to be engaged with the magnetic head. In this system, the head and the tape can be positioned accurately. However, if the front opening of the conventional Phillips-type cassette is made larger so that the tape can be pulled out, the cassette cannot be interchanged with a conventional audio signal recording and reproducing cassette. Thus, the range of its application is limited.